Fittings for pipes are known, made of plastic or metal, comprising a main body, also being made of plastic or metal, which internally accommodates an outer pipe, in order to connect it to a fluidic circuit placed upstream or downstream of the fitting, and fastening means, also made of metal or plastic, able to be tightened to the main body.
Generally, these fastening means comprise a nut that can be screwed on a corresponding threaded region of the main body or, alternatively, a nut, or bush, constrained to the main body by tie rods, consisting of screws or connecting bolts, for example.
Further, the main body accommodates an annular sealing gasket, of truncated cone, cylindrical or toroidal shape, preferably made of rubber or deformable synthetic material, and a notched, or anyhow deformable, blocking ring nut (also termed “ogive”), also being truncated cone, cylindrical or toroidal, able to ensure, once the nut is tightened to the main body, both the sealing, and the blocking of the pipe to the fitting in stable position, respectively.
According to the prior art there exist fittings of the above mentioned type, wherein advantageously the annular sealing gasket and the blocking ring nut are realized in a single piece.
In all of the above fittings, the outer pipe blockage within the fitting body and the fluidic sealing of the fitting itself are usually ensured by the interference coupling of conical walls, usually those of the inner surface of the fitting body and/or the relevant fastening nut with the outer walls of the blocking ring nut and/or in case of the annular gasket, such that the tightening of the nut to the main body of the fitting determines the progressive engagement of the blocking ring nut, and possibly the gasket, with the inner walls of the fitting, which walls, due to different taper, cause the substantially radial crushing of such a blocking ring nut (ogive), and possibly the annular gasket, on the outer pipe placed within the fitting itself.
This type of fitting, although rather efficient, has the drawback of not being easily connectable to the outer pipe, not allowing in fact the insertion of the pipe within the fitting, when the nut is combined, or even only partially screwed to the main body. In substance, before introducing the pipe within the main body of the fitting the fastening nut, the blocking ring nut (ogive) and the annular sealing gasket must be fitted (suited) onto the pipe and then, subsequently, when the pipe is completely introduced within the main body of the fitting, progress to first combining, and then tightening, the nut to the same main body.
This is mainly due to the fact that the annular sealing gasket, truncated cone or of other shape, if fitted within the main body before the pipe insertion, would be subjected, during the pipe insertion to a hardly amendable deformation, with subsequent sensitive reduction of the sealing efficiency of the fitting. The shape of the blocking ogives, with inner diameter substantially like outer diameter of the pipe and usually not elastically deformable, especially in radial direction, also helps avoiding that the pipe can be put into the fitting, or possibly withdrawn, after this last one has been almost totally pre-assembled.
This problem is due to the strong friction and/or interference generated between the inner surface of the annular sealing gasket, made of rubber or synthetic material, and the outer surface of the pipe, made of metal or plastic, during the insertion of the pipe within the fitting, and also to the presence of a blocking ogive which, during the pipe insertion, urges the annular sealing gasket to deform or results of hard suitability or yet axially moves, hampering the possible pipe insertion.
Therefore these drawbacks are responsible of a highly complicated, slow and not always effective connection between pipe and fitting.
U.S. Pat. No. 3,140,107, for example, illustrates such a fitting that, even provided with an abutment ring interposed between the sealing gasket and blocking ogive, provides, mainly due to the shape and properties of said blocking ogive, adopting the ring form with truncated cone development, that the pipe is preventively fitted into the tightening nut, and thus into said ogive and sealing gasket, with relevant abutment ring, before assembling the entire fitting.
The object of the present invention is, therefore, achieving a fitting able to make faster and, anyhow, reliable, the connection between the fitting itself and an outer pipe, avoiding the above mentioned technical drawbacks.
Further object of the present invention is achieving a connection method between outer pipe and fitting which is simple, fast and effective.